Halogenated hydrocarbon composition



Patented Nov. 9, 1948 HALOGENATED HYDROCARBQN COMPOSITION Frank Clarkand Edward'L'. Raab, Pittsfield," Mass, assignors to: General ElectricCompany, a corporation of New York No Drawing. Application June 18,1945, Serial No. 600,214

l fi'Glaims. (01. 252-6317) 1 l The present application is acontinuation-in part of our prior application Serial No. 440,100, filedApril 22, 1942 (now abandoned).

The present invention comprises improved insulating and dielectriccompositions for use in electrical devices, such for example astransformers, capacitors, cables and circuit breakers; and its object isto render innocuous deleterious decomposition products of halogenatedcompositions which are employed for dielectric and insulating purposesin such devices.

Electrical apparatus, such for example as transformers, switches, cablesandzthe like,ordinarily' comprise metal partsandcommonly alsoinsulating'material, such for example aspaper, cotton, or othercellulosic products. These two types of construction materials are bothsubject to chemical attack by hydrogen chloride, or other chemicallyactive halogen compounds. The formation of rust is accelerated on ironsurfaces by metallic halide compounds. Rust, or any floating metalliccompounds, constitutes a hazard to the proper functioning ofliquid-cooled apparatus, particularly if present in apparatus in whichthere is relative motion of parts. Particles of rust or similar materialif loosened during the use of the apparatus may be drawn into a regionof intense dielectric field by the circulation of a liquidinsulating andcooling medium, and lead to electrical breakdown and failure of theapparatus. 1

Hydrogen halides, likewise, chemically attack paper, cotton and othercellulosic insulation, leading to increased electrical losses anddecreased i mechanical strength of such insulation.

In accordance with our invention, hydrogen 1 halide formation ismaterially reduced and, in favorable instances, even entirely eliminatedby associating halogenated hydrocarbons or mixtures thereof with afixative consisting of polycyclic compounds containing at least oneheterocyclic ring and a plurality of hetero atoms, at least one of whichis nitrogen. Preferably such polycyclic stabilizers are chosen from thealkaloid group, including brucine and nicotine. The following compoundsconstitute additional examples of such fixatives: purine, xanthine,theobromine, caffeine, quinine, strychnine, parahydroxy phenylmorpholine, nitron, diphenyl piperazine and phenyl methyl pyrazolone.Included are derivatives of five-numbered heterocyclic ring compoundswhich have two hetero atoms, for ex ample, z-methyli-phenyl oxazole, and4-phenyl- 2-methyl thiazole.

Halogenated hydrocarbons of many kinds (known as askarels) have beenused or proposed for electrical insulating, dielectric andheatdissipatin'g: purposes. Examples of halogenated aryl compounds which aresuitable for the insulating field are-disclosed int'the U. S. LettersPatent 1,931,455; patented October 17, 1933; 1,999,004, patentedApril23; 1935; 2,012,301 and 2,012,302, patented August 27, 1935; 2,033,612,patented March 10; 1936; and-2,198,473, patented April 23, 1940. Theliquid insulating-and dielectric compositions described inthese patentsinclude chlorinated benzene and various chlorinated diaryl'compounds,which are stable under normal conditions of operation of electricdevices in which they are used. Such compounds, however, are subject todecomposition under abnormal conditions, for example, when an electricarc occurs in contact therewith or when they are subj ected to acombination of electric stress and elevated temperatures.

The relative amount of protective fixative compound present incompositions embodying our in Vention depends upon the nature of theelectrical apparatus and the amount of electrical arcing to which thecomposition will be exposed in the ordinary use of the apparatus. Insome electrical devices, such, for example, as transformers, thedecomposition effected by an electric arc occurs only in the event ofabnormal contact of an electric arc with the halogenated composition.Arcing may never occur during the normal life of an electrictransformer, and ordinarily would only be caused by such abnormalconditions as will result in failure of a transformer. In cooling andinsulating compositions subjected only to occasional contact with anelectric arc, amounts by weight as small as 0.1 per cent and notexceeding about two per cent of the protective agent normally aredesirable for protection. In electrical switches, in which the arcingelectrodes are immersed in a liquid-halogenated hydrocarbon and in whichrecurrent arcing occurs during the normal use of the switch, largeramounts of fixative compound are required. For example, five to ten percent of protective stabilizer compositions advantageously may be presentin compositions frequently subject to the decomposing effect of anelectric arc. The stabilizer compound should be substantially insolublein water.

Insulating paper in electrical apparatus when in contact withhalogenated hydrocarbon is deleteriously affected and may even bedestroyed by the presence of hydrogen halide in such hydro carbon.Hydrogen halide may be formed by an electric discharge due to failure ofthe apparatus. It has been established by experience with insulatingpaper when in contact with a mixture of chlorinated diphenyl andtrichlorbenzene contaminated by hydrogen chloride that the paper becomesblackened and loses most of its tensile strength in less than one day.Under similar conditions, except for the presence of a stabilizer suchas herein described in the chlorinated com-- position, such paper isunaiiected.

The benefits of our invention can be obtained in various ways other thanby solution in the chlorinated aryl hydrocarbon. The fixative compoundmay be added to the halogenated composition subsequent to the occurrenceof arcing. For example, the fixative compound can be added to ahalogenated composition contained in a transformer or other electricaldevice by manual or automatic means upon the occurrence of an electricalarc, thereby causin the protective compound to immediately act uponhalogen halide or other decomposition product which has been formed bythe action of the arc.

What we claim as new and desire to secure by Letters Patent of theUnited States is:

1. A liquid composition suitable for insulating and dielectric purposesconsisting essentially of the combination of normally stable halogenatedaromatic hydrocarbon compounds and a fixative for halogen decompositionproducts consisting of a polycyclic compound containing at least oneheterocyclic ring and a plurality of hetero atoms at least one of whichis nitrogen, said fixative constituting at least 0.1 to 10 per cent ofsaid composition.

2. A liquid composition suitable for insulating and dielectric purposesconsisting essentially of the combination of normally stable chlorinatedaromatic hydrocarbons and about 0.1 to 10 per cent of a polycycliccompound containing at least one heterocyclic ring and a plurality ofhetero atoms.

3. A liquid composition suitable for insulating and cooling electricaldevices consisting essentially of chlorinated diaryl hydrocarbons andabout 0.1 to 2 per cent of a polycyclic compound containing at least oneheterocyclic ring and a plurality of heteroatoms at least one of whichis a nitrogen atom.

4. A composition consisting of chlorinated diaryl hydrocarbons and afixative consisting of 0.1 to 10 per cent of b-rucine.

5. A composition consisting of chlorinated diphenyl and about 0.1 to 2per cent of brucine.

6. A' liquid composition consisting essentially of halogenated diarylhydrocarbon compounds and about 0.1 to 10 per cent of a fixativeconsisting of nitron.

FRANK M. CLARK. EDWARD L. RAAB.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 1,996,717 Carlisle Apr. 2, 19352,111,253 Stoesser Mar. 15, 1938 2,160,944 Coleman June 6, 19392,227,637 Engelhardt Jan. 7, 1941 2,268,146 Hanson Dec. 30, 1941

